Study: Value-Added Has Real Value for Students
An eye-catching new statistical analysis by economists at Harvard and Columbia universities finds that having a high-quality teacher for even one year can have a measurable long-term impact on students’ career outcomes.
The study tracked one million children from a large urban school district from 4th grade to adulthood. The researchers gauged the effectiveness of their teachers in grades 4 through 8 through value-added analysis, calculating their impact on student standardized test scores over time, with adjustments made for differences in student characteristics.
The study is reportedly the most extensive examination to date of the effectiveness of value-added rankings of teachers.
The researchers found that students who were assigned teachers with higher value-added ratings ended up being “more successful in many dimensions,” including college graduation rates, earnings, and savings.
On average, the study concludes, having a teacher with a high value-added rating for one year raises a student’s lifetime income by $50,000. Replacing a teacher who has a low value-added rating with a teacher of just average quality, according to the study data, could mean earnings gains of as much as $52,000 per student—or more than $1.4 million for the class as a whole. The teachers' impact on earnings were similar whether the students were from high- or low-income families.
The researchers also found that, when a teacher with a high-value score joins a school, tests scores immediately go up in that teacher’s grade and subject.
The findings, according to the study’s authors, show that “great teachers create great value and that test score impacts are helpful in identifying such teachers.” However, they also cautioned that use of value-added ratings in teacher evaluations could “induce counterproductive responses … such as teaching to the test or cheating.”